A telecommunication switch is used to write message traffic over a network. Usually, it comprises a chassis or housing containing circuitry on a multiplicity of printed circuit cards which slide into the chassis and plug into a motherboard inside the chassis. The various communication lines are plugged into connectors on those cards, the connectors being exposed at the front and/or back of the chassis. The actual switching may be controlled by a central processor unit (CPU) contained on one or more of the cards in accordance with programs and instructions provided from an external keyboard. The chassis usually also contains a power supply for supplying power at various parts of the switch. Examples of such switches are disclosed in U.S. Pat. No. 5,398,161 and pending application Ser. No. 08/936,489, filed Sep. 16, 1997. The contents of said patent and application are hereby incorporated herein by reference.
In the construction of telecommunications switches of this general type, it is customary to incorporate into the switch various latch mechanisms to facilitate the insertion and withdrawal of the printed circuit cards from the switch chassis. Usually, the latches are mounted to opposite sides of each printed circuit card. When the card is slid into the chassis, the latches may be actuated to drive the card to a home position which causes connector(s) at the rear edge of the card to mate with corresponding connector(s) on the motherboard within the chassis. Movement of the latches to an unlocked position disconnects the card from the motherboard so that the card can be slid easily out of the chassis.
The prior printed circuit card injector/ejector mechanisms are disadvantaged in that they occupy a relatively large amount of surface area on the printed circuit card. This reduces the available space on that card for electrical components and printed circuit paths. Resultantly, to give a switch a given switching capacity, either the cards have to be made larger or more cards must be used thereby increasing the overall size of the switch.
The conventional printed circuit cards used in telecommunication switches invariably have metal face plates at the fronts of the cards. When all of the cards are seated properly in the switch chassis, the plates combine to form a front panel which is supposed to provide a shield to minimize the emission of electromagnetic radiation at the front of the switch. However, the prior injector/ejector mechanisms for the printed circuit cards were not designed with this objective in mind because those mechanisms require relatively large openings in the face plates in order to function properly. These openings constitute holes in the electromagnetic shield at the front of the switch through which electromagnetic radiation can escape from the interior of the switch.